Apparatus for logging wells



A ril 2, 1957 ARPS 2,787,759

APPARATUS FOR LOGGING WELLS Filed Aug. 31 1950 3 Sheets-Sheet l Jami/ x05 file/=5,

INVENTOR.

,Qrra A/EK April 2, 1957 .1. .1. ARPS APPARATUS FOR LOGGING WELLS 5 Sheets-Sheet 2 Filed Aug. 31 1950 w m N w FIG. 3.

Arroe/vix April 2, 1957 J. J. ARPS APPARATUS FOR LOGGING WELLS 5 Sheets-Sheet 3 Filed Aug. 31, 1950 A INVENTOR.

flrro/e/vs w M w M w E APPARATUS FOR LOGGING WELLS Ian J. Arps, Tulsa, Okla.

Application August 31, 1950, Serial No. 182,604

2 Claims. (Cl. 324-1) This invention relates in general to the exploration of the geological strata traversed by earth boreholes and more particularly to methods and apparatus for determining the electrical characteristics of the various subsurface geological formations penetrated by a well borehole, particularly methods and apparatus by means of which simultaneous electrical logging and drilling of well boreholes may be carried on.

This application is a continuation in part of the applicants co-pending application, Serial No. 619,629, filed October 1, 1945, now Patent No. 2,524,031. The subject matter of this earlier filed application relates to a system of earth borehole logging in which signals representing an electrical characteristic of earth formations penetrated by the borehole are impressed upon and transmitted through the drilling fluid circulating through a drill string, without any appreciable effect upon the flow of the drilling fluid. The subject matter of the present disclosure relates to a logging system in which the signals representing the results of investigations in the borehole are transmitted by way of positive changes of considerable magnitude made in the circulation of the drilling fluid in the drill string, as, for example, by pressurechanges created by valving the flow of drilling fluid through a valve means in the drill string.

Many prior methods have been proposed for measuring the various characteristics of the subsurface formations penetrated by a borehole and a common practice has been to employ an insulated conductor cable for supplying electrical energy from the surface to the well logging or investigation apparatus within the borehole, and a separate insulated conductor therein for transmitting the response of the investigation apparatus to an indicating means at the surface of the borehole. Such logging apparatus can only be run into the Well at intervals after the drill pipe is removed from the borehole and in many cases it is found that possible productive horizons unknowingly have been drilled through or passed by during the drilling, causing subsequent completion or continuance of drilling to be difiicult and costly. It is also known that during the process of drilling through a prospective producing formation water from the drilling mud invades such formation and if too much times passes between the time of drilling through the formation and the time the electric logging survey is made, this invasion is often of such extent as to change the natural electric resistivity of the formation sufficiently to result in confusion in the proper interpretation of its characters.

These disadvantages relative to the undesirable invasion of the penetrated formations by liquid from the drilling fluid are largely overcome-by the present inventionbe cause the natural electric resistivity or other electrical measurement is made substantially, simultaneously with or immediately after the formation is drilled into, and thus before substantial infiltrations and flooding of the drilled formation by water from the drilling fluid can take place.

2,787,759 Patented Apr. 2, 1957 apparatus for logging the formation characteristics of a well borehole, continuously during drilling operations or at suitable intervals thereof, wherein the source of electrical energy for the investigation apparatus is generated or supplied adjacent the bottom of the well borehole and the signals related to the electrical characteristics of the adjacent penetrated strata to be measured are transmitted to the top of the well borehole without the use of any auxiliary conductors, cables or the like, and the signals are picked up by surface indicating apparatus and from which the values of the electrical characteristics to be measured are obtained and are constantly available to the drilling operator.

More specifically but not by way of limitation, this invention utilizes the circulation of the drilling fluid in the drill stem for supplying the electrical energy utilized by the investigating apparatus. Furthermore, the drilling fluid stream is utilized as a transmission medium for trans mitting flow variation signals from the investigation apparatus within the well borehole to the top of the well.

It is accordingly an object of the present invention to provide a method and apparatus for continuously indicating the electrical characteristics of the subsurface, geological formation penetrated by a borehole and which indication can be continuously transmitted to the surface of the borehole without the necessity of employing the usual electrical connecting cables.

It is another object of this invention to provide a method and apparatus for logging a well borehole during the process of drilling and in which variations in the physical properties of the penetrated strata will produce variations in an electrical investigation apparatus located opposite the strata, which variations are transmitted to the surface of the borehole through the drilling fluid to provide, at the top, a continuous indication of the electrical characteristics of the penetrated strata.

A still further object of this invention is to provide a method and apparatus for logging the electrical characteristics of freshly drilled subsurface formations wherein a periodic valving device is utilized in the drill string to periodically vary the flow therethrough of the circulating drilling fluid stream at a frequency representative of the electrical characteristics of the freshly penetrated formations to be measuredv .The objects of this invention are attained in brief by utilizing the drilling fluid circulating stream as a signal transmission medium and creating in the drilling fluid stream, at a remote point within the borehole, periodic variations in its rate of flow, the frequency of variation of which is modified by suitable means within the well borehole in accordance with the electrical characteristics of the adjacent subsurface formations to be measured, and utilizing the thus affected periodic variations in the character of the fluid flow appearing at the earths surface at the top of the well borehcle to generate or form 4 electrical signals which are functions of the said fre- In general, the present invention provides a method and.

quency of variation of fluid flow and can be measured and which are therefore representative of the beforementioned electrical characteristics of the subsurface formations.

Other objects, advantages and features of novelty will i be evident hereinafter in the more detailed description of the invention.

In the drawings which illustrate preferred embodiments and modes of operation of the invention and in which like reference characters designate the same or similar parts throughout the several views:

Figure l is a diagrammatic elevational view of a drilling rig showing in vertical section a typical well borehole and rotary drilling string in which the apparatus of the invention is employed;

' Figure 2 is a longitudinal sectional view of the lower portion of Figure 1 showing therein an enlarged detail View of the portion ofthe logging'apparatus illustrated schematically in Figure 1 in the lower part of the drill collar;

Figure 3 is a longitudinal sectional view of the sameportion of the apparatus illustrated. Figure 2 but cork tain ng an alternative form of logging apparatus} Figure 4 is a schematic view partly in cross-section and Figure 5 is a cross-sectional view of a modification of a portion of theapparatusof Figure 4.

Referring now primarily to Figures 1 and 4, reference character 2 indicates a Well derrick disposed over a borehole 4 in which is located a string of drill pipe 6 extending through a rotary table 8 on the derrick floor. The upper end of the drill stem 6 is attached to a square kelly 10 which passes through and is grasped by the table 8, which in turn'is rotated by a conventional drive means from a suitable source of motor power such :as the engine illustratedat 12. The drill string is supported through thelrellylfi and a swivel 11 by means of a hook 14 extending downward from a traveling block 16 whichis in turn supported by suitable drilling lines 19jwhich pass over a crown block 17 in the top of the derrick. A mud pump 24 takes drilling mud from a sump 22 and dis charges drilling mud under pressure through pipe line and swivel 11 into the top of the kelly 10 and drill stem 6.

Connected in an intermediate point in the mud line 20 is a surface detecting device 25 which will be described hereinafter in detail in connection with Figure .4. The lower end of the drill stem 6 is provided with a'drill collar 28 of an increased outside diameter and having a suitable drill bit 36 connected to the lower end thereof.

Thelogging apparatus to be hereinafter referred to is disposed within the drill collar. 28 a suitabledistance above the top of the drill bit 3%) and is preferably contained in a cylindrical housing unit in the position illustrated in dotted lines at 32 in Figure 1. The housing32 through the conductors 49 and 48 to the electrode 52,

is adiiect current 6i"alternatihgcurrent electric motor 54 connected in series therewith and of such type that the speed of rotation varies directly with or in accordance with a suitable function of the magnitude of the current flowing therethrough.

From the foregoing it will be apparent that the complete circuit activated by the generator 44 includes in series therewiththe variable speed'motor 54, a portion of the drilling fluid in the annular space surrounding the electrodes 53 and 52 and a portion of the formation strata extending between and located adjacent the electrodes 50 and 52. The electrical resistance of the adjacent formation opposite the two electrodes "50 and 52 and also to some extent that of the drilling mud passing through the annular space surrounding the drill collar and between the annular electrodes 50 and 52 and the walls of the is fluid tight with the exception of certain inlet and outlet ports and passages as will be'hcreinafter more fully explained.

Referring now to the beforementioued investigation or logging apparatus in detail and more particularly to Fig: ures 2 and 3, a vertical turbine 34 is arranged inside the housing 32 in a position above the rotary bit and to which an inlet flow passage 36 is provided in communication with the drilling fluid or mud present in the drill stem 6 outside of the housing 32. The drilling fluid flow-f equipped with a voltage regulator (not shown). in orderto maintain its output voltage at a constant value independent of variation in the speed of the turbine 34 which variations would normally be caused by any fluctuations in the velocity or pressure of the mud stream flowing downward in the drill stem. The electrical output or cur- 7 rent from the generator 44 is conducted by conductors 46 and .48 extending through respective apertures 4 5 and 47 in the drill collar, to two metal eIeetroZl'eband's-SG and 52 respectively. These annular electrodes are insulated fromand are disposed around the drill collar 28 111 vertically spaced relationship. The outer surffaceof the V drillcollar is provided with an insulating sleeve or covering 53 which is interposed between the-annular electrodes and52 and the outer surface of the drill collar. In the electrical circuit extending from the generator .44

borehole, .will thus determine the amount of current flowingtlirough the beforernentioned series ClIClllfWhlClllll: turnwilldetermine the speed of rotation of the motor 54."

The motor 54'. is coupled through a shaft 58 with? generatondfl', preferably an alternating current generator} whichIisjdisposed immediately thereabove in the'liou'si'ng 32; The generator 6flinthe case where it is an alternat ing current generator is preferably constructed in such a manner thatthe frequencyof the alternating current.

current path through the drilling fluid and the adjacent.

strata located'op'posite' the two electrodes 50 and '52. From the foregoing, it will be apparent'that during the drilling. operation or during an interval. thereof, if a stratum is penetrated which contains mainly salt water.

normally having a low electric resistivity, the electrical outputor current througlrthe series circuit comprising" electrode 59,.conductor 46, generator 44, conductor 49', motor 54, conductor 48 and electrode 52, and the before} mentioned surrounding formations, will be increased, thereby causing a corresponding increase in frequency of the alternating current generated by the generator 60. However, on the other hand, when an oil or gas bearing stratum is penetrated, which is normally characterized by a higher electrical resistivity, then the current through the beforementioned series circuit will be reduced in ac} cordance with the increased electrical resistance of the beforementioned adjacent oil or gas bearing strata, which inturn will result in a reduced speed of the motor 54 and: a: corresponding lower frequency of the alternating current output from the generator From the foregoing,.it will beapparent that the generator .44 and motor.

54 are,v operating inv aseries circuit which includes the formation in which. the characteristic of the formation is measured'in' terms. of its electrical resistivity Either direct current. or alternating current may be utilized in.

this circuit without changing the basic principle of the inventionr :In the case where an alternating current generator is employed at 44 and an alternating current: motor ac-54, theannular electrodes 5%) and .52 willbesupplied with-analternating current, and in the casewhere' a direct current generator is employed at 44'and a direct current motor at 54-the electrodes will accordingly be supplied.

with a direct'current. In the case of the use of an altermating current the formation characteristic measured may,

be considered as the impedance ratherthanthe normal:

resistivity. use of an alternating current may be pre erable cases where tlie electrolytes in the-drilling fluid causepolarization of the electrodes 50 and 52.

Disposed immediately above the generator 60, within the housing 32 is an,electromagrietically operated. valv ing mechanism .62 which .is connected to the generator through conductors 63: and 64. The valving mechanism comprises a solenoid electromagnet field coil 6 5,".a magnetizedsolenoid. armature or. plunger 66 and a conically -shaped valvehead :67 fixedon the upper end of the plunger 66. The valve head 67 working in conjunction with the adjacent conical surface 68 is adapted, upon being moved longitudinally relative to the surface 68, to valve the flow of fluid therebetween. The valving mechanism 62 is thus constructed so that it will have a valving action upon the drilling fluid stream flowing down through the drill collar and through the passageway 69, and since the windings of the solenoid 65 are connected through conductors 63 and 64 to the output connection of the generator 69 as beforementioned, the valving action would occur at a frequency corresponding to that of the alternating current from generator 61 The solenoid armature or plunger 66 is permanently magnetized with opposite magnetic poles at opposite ends thereof. When the solenoid winding 65 is energized by alternating current the plunger '66 is thereby caused to have a longitudinal, reciprocating motion through the solenoid winding in synchronism with the alternating current, resulting in valving of the mud stream flowing between the valve head 67 and the surface 68 and through the drill pipe at a frequency equal to the frequency of the alternating current. This variation in flow will appear in the drill pipe at the top of the well where it may be detected by one of the beforementioned detecting devices which are illustrated in detail in Figures 4 and and which will be described hereinafter.

Referring now primarily to Figure 4, the detecting device indicated generally at 26 in Figure 1, comprises a housing member 70 connected to the mud line 20. The housing member 70 is formed of two portions, an upper hemispherical head or cover section 72 and a lower conical section 74 secured together by bolted flanges as shown at 76. interposed between the flanges is a suitable flexible diaphragm 78 which may be subject to gas or air pressure in the chamber space 79 under the cover section 72. To equalize the gas or air pressure with the drilling fluid pressure in line 20 a surge chamber 71 is preferably used which consists of a vertical vessel 73 communicating through a bottom connection 75 with the drilling mud line 2%) and through'an upper pipe connection 77 to the space 79 in the housing 711 above the iaphragrn 78. A floating ball 81 is provided in the vessel 71 to keep the gas from bleeding out into the mud line 20 when the pumps 24 are shut down and the liquid level therein falls to the bottom of the vessel 71. An adjustable needle valve 33 is provided in the pipe connection 77 to allow relatively slow changes in mud pressure occurring during drilling to become equalized on opposite sides of the diaphragm 78. A coil 89 is attached to the diaphragm 78, which is thereby adapted to he vibrated in a strong magnetic field produced from a permanent field magnet 32. The field magnet 82 is secured to the top of the cover section 72 by means of a bolt 84. Movement of the diaphragm 78 and the coil 80 attached thereto is caused by pressure variations in the pipe 20 incident to the flow variations caused by the valving mechanism 62 and transmitted through the drill stem and'through the pipe 2% Slight movement of the diaphragm 78 and coil 39 attached thereto will induce an alternating current or potential in coil 81) which is passed through conductors 86 and $7 to an amplifying unit 88, of aconventional type. The output voltage or current generated by the coil 8tlwill have a frequency 1 quency. The remaining higher frequency alternating signal component passing through the high pass *filter9ll is conducted to an electrical transducer 92 which is de signed to translate or transform the frequency modulated input signal into a corresponding amplitude modulated output signal. Since the frequency of the input signal generated in coil and passing through the high pass filter 90 necessarily varies in accordance with the variation of the frequency of the valving action of the valving device 62 which in turn is-representative of the resistance or impedance of the borehole strata opposite the electrodes 50 and 52, the amplitude modulated output signal from the transducer 92 will therefore likewise vary in amplitude in a similar manner representative of the resistance or impedance of the beforementioned strata. From the transducerf92 the amplitude modulated alternating signal is transferred to a rectifying unit 94 in which the amplitude modulated signal input thereto is changed into a D.-C. or unidirectional signal output. As illustrated in Figure 4, the resultant D.-C. signal from the rectifier unit 94 may be transferred to a sensitive arnmeter or galvanometcr such as illustrated at 96 from which, if desired, the magnitude of the D.-C. signal can be read directly. However, as shown in Figure 4, the ammeter or galvanometer 96 may be connected in series with a movable coil 100 having a mirror 102 attached to the torsion supporting conductor member 194 which is in turn connected through conductor 105 with the rectifier 94. The opposite side of the rectifier 94 is connected to the ammeter 96 through conductor 103. Surrounding the coil 101) is a stationary permanent field magnet 106 which produces a magnetic field which. upon transmission of a current through the coil 10!) causes rotation of the coil with a corresponding angular rotation of the mirror 152. A source of light 108 is ar ranged to throw a light beam onto the mirror 102 from which it is reflected onto a sensitive photographic film 119 disposed in the path thereof, in order that a permanent record of the logging data may be photographically recorded thereon as illustrated at 111.

The film 110 is disposed in a suitable light proof container (not shown) on rolls 112 and 113 and the take-up roll 112 is directly connected through a drive shaft 114 to a gear box 116 which in turn is coupled through a pulley 118 and cable 119 to the traveling block 166. From the foregoing it will be apparent that the film 110 may be scaled longitudinally to indicate the depth within the borehole to which-penetration of the bit has progressed and with the gear arrangement 116, the photographed graph 111 on the film llltl'will indicate the electrical characteristics of the formation at the exact depth of the drill ing operation.

Referring now to Figure 3'showing a modification of the investigating apparatus, parts of the apparatus such as the turbine 34 impelled by the drilling fluid, the generators 44 and 66 may be identical with those of the embodiment disclosed in Figure 2. However, an alternative form of valving device is utilized in lieu of the one shown at 62 in Figure 2. The alternative valving device comprises a balanced piston 126 reciprocable longitudinally within a cylinder 127 formed in the upper end portion of the housing 32. A plunger 128 extends from the lower end of the piston 12.6 through a suitable stuifing box 129 into the interior of the housing 32 and into the solenoid electroma'gnet 65. 'The piston 126 is provided with longitudinally extending pressure equali zation ducts 13% extending from end to end thereof. The central portion of the piston is provided with a circumferentially extending annular channel or groove 131 which in the normal position of thepiston 126 serves as a flow channel interconnecting the upper and lower annular drilling fluid ducts 133 and 134,.respectively. Upon effecting longitudinal reciprocation of piston 126 .the flow passage between theupper fluid ;-passage 133 land the lower fluid passage 134 is valved as hereinafter more fully described.

In operation the alternative apparatus shown in Figure 3 functions in a manner similar to that of the preferred embodiment shown in Figure 2 in that an alternating current is transmitted from the generator 60 and with a frequency which varies directly with the speed of the variable speed motor 54 dependent upon and repre sentative of the resistivity or impedance of the formation surrounding the well borehole adjacent the electrodes 50 and 52. The generator 60, as in the previous illustration, is directly connected through conductors 63 and 64 to the windings of the solenoid electromagnet 65. Since the plunger 128 is permanently magnetized in the same manner as hereinbefore described in connection with plunger 66 the solenoid will induce longitudinal reciprocation of the plunger 128 when it is excited with the alternating current applied to it from generator 60 through the beforementioned conductors 63 and 64. Thus the piston valve 126 is caused to reciprocate longitudinally and to thereby periodically valve the passage of drilling fluid from the upper channel 133 to the lower channel 134. A periodic variation in the rate of flow of the drillling fluid will thus be induced which will be reflected in a similar periodic variation in the flow of the drilling fluid in the drill stem at the top of the well borehole and through the pipe connection to which the detecting apparatus of Figure 4 is connected. As in the case of the apparatus of Figure 2 the pressure variations due to the variations in flow will be transmitted to the diaphragm 78 and the resultant movement of the diaphragm and coil 80 will generate a corresponding alternating current or potential in the coil 80 which is conducted through conductors 86 and 87 to the amplifier unit 88 and thence through the circuit to the recording apparatus as hereinbefore described.

Referring now to Figure 5 in which a modified version of the detecting device is shown, a housing is shown formed of two oppositely positioned, dome-shaped head members 146 and 141 separated by and bolted to an intermediate, cylindrical body member 142, the sections being secured together by suitable bolted flanges as shown at 143. interposed between the two flanged connections between the head members 140, 141' and the center body member 142 are a pair of flexible diaphragms 144 and 145. A coil of the same type as that shown at 86 in Figure 4 is attached to the inner face of the flexible diaphragm 145, the coil 80 being thereby adapted to vicrate in a strong magnetic field from a permanent magnet 32 of the same type as that hereinbefore described in connection with Figure 4. The permanent magnet 82 is secured stationary within the center body member 142 by means of a plurality of radially positioned, interconnecting web members as shown at 146 and 147, the web members making connection at their outer edges with the inside surface of the cylindrical body member 142 and at their inner edges with the metal of the magnetized member 82.

The opposite head members 140 and 141 are connected through suitable pipe connections 148 and 149 to the drilling mud pipe line 20, the points of entrance of the said connecting pipes 148 and 149 into the line 20 being on opposite sides of an orifice plate 150 bolted between suitable flanges in the pipe line as shown at 151. The space within the central cylindrical body member 142 between the flexible diaphragms 144 and 145 is adapted to-be iiiled with oil or other similar liquid which will be Movement of the diaphragms 144 and 145 and the coil attached to diaphragm will be caused by differential pressure variations transferred through connections 148 and 149 from either side of the orifice plate 150 resulting from corresponding variations in the rate of flow of fluid through the pipe line 20 caused by the valving action of the apparatus of Figures 2 and 3 as hereinbeiore described. The resultant slight movement of the diaphragm 145 and the coil 80 attached thereto will induce an alternating current or voltage'in the coil 80 which current or voltage is passed through conductors 86 and 87 to an amplifying unit such that that shown at 83 in Figure 4, and thence through the electrical apparatus of the same or similar type as that illustrated in Figure 4.

The terms measuring the frequency, amplitude or the like as employed in the specification and claims are not to be limited in meaning to the actual quantitative determination of such values but are to include the control or actuation of any circuit, indicator or recorder means or device such as a meter or galvanometer or the like device whereby a visual indication or graphical record of a measure of such values or an indication or graphical record of a value or values which are indicative of, representative of or bears a predetermined functional relationship to the aforesaid values may be obtained.

It is to be understood that the foregoing is illustrative only and that the invention is not limited thereby but may include various modifications and changes made by'those skilled in the art without distinguishing from the spirit of the scope of the invention as defined in the appended claims.

What is claimed is:

1. In apparatus for making well borehole quantity measurements while drilling including a drill stem having a fluid circulating duct therethrough and pump means for circulating fluid down through said duct in said drill stem; the combination comprising: flow restriction means in said drill stem in the vicinity of the lower end thereof actuatable for effecting a variable resistance to flow of fluid through said duct; actuating means to actuate said flow restriction means; sensing means for taking measures of the varying value of an electric quantity exisiting within a well borehole; timing means responsive to the said measures taken by said sensing means operatively connected to said actuating means for actuating said flow restricting means at times having an interval therebetween bearing a predetermined functional relationship to the said value of said quantity.

2. In apparatus for making well borehole quantity measurements while drilling including a drill stem having a fluid circulating duct therethrough and pump means for circulating fluid down through said duct in said drill stem; the combination comprising: flow restriction means i in said drill stem, in the vicinity of the lower end thereof actuatable for effecting a variable resistance to flow of fluid through said duct; actuating means to actuate said flow restriction means; sensing means for taking measures of the varying value of an electric potential existing within a Well borehole; timing means responsive to the said measures taken by said sensing means operativelyconnected to said actuating means for actuating said flow restricting means at times having an interval therebetween bearing a predetermined functional relationship to the said value of said quantity.

References Cited in the file of this patent UNITED STATES PATENTS 2,297,399 Fuscaldo Sept. 29, 1942 2,329,732 Varney et al. Sept. 21, 1943 2,352,833 Hassler July 4, 1944 2,380,520 Hassler July 31, 1945 2,435,934 Varney et al. Feb. 10, 1948 2,480,674 Russell Aug. 30, 1949 2,524,031 Arps Oct. 3, 1950 

